As network bandwidth and transmission speed increases, it is becoming more common for individuals and corporations to send and receive voice data over packet switched networks such as the Internet or other IP (Internet Protocol) based networks rather than through the traditional circuit switched telephone system. The use of such packet switched networks to send and receive voice or audio data is referred to as VoIP (Voice over IP), IP Telephony, or Internet telephony. VoIP is typically thought to provide benefits such as lower per-call costs, lower infrastructure costs, and easier expandability.
In addition to voice data, VoIP connections may send other audio data such as DTMF (Dual Tone Multi-Frequency) data. DTMF is the system used by touch-tone telephones to indicate which key on a telephone keypad has been pressed. DTMF assigns a specific frequency (consisting of two separate tones) to each key so that it can easily be identified by a receiving system. DTMF data may be used as part of an interactive voice response system in which a user responds to voice prompts by pressing keypads to navigate through various options provided by the system. For example, a user may hear bank account information by calling a number provided by the bank, and pressing keypad numbers in response to prompts to provide account numbers and access codes. Similar systems such as payment systems allow users to enter credit card numbers to make payments over the phone.
Unfortunately, due to the nature of network data transmission, it may be possible for third parties to intercept or “snoop” audio data while it is transmitted on the network. For example, a third party may be able to determine a user's account number and access codes, credit card information, or other private data by scanning audio data transmitted over a network for DTMF tones present in the data. The third party may then use the DTMF data to make unauthorized access to a VoIP user's financial or other private data. While it is possible to encrypt all VoIP data for a particular session, this typically requires more processing power than is desirable in the VoIP environment. As a result, there is a need in the art for the embodiments of the present invention.